Published in International Journal of Gynecological Pathology · September 2019
TP53 gene mutations manifest in three distinct p53 IHC staining patterns — overexpression, wild-type, and null. These patterns are used to subtype ovarian cancer, and accurate interpretation is essential for clinical decision-making. Misinterpretation — particularly reading null expression as wild-type — has direct consequences for subtyping accuracy. This study investigated whether a structured cell line–based reference panel could improve the reliability and consistency of p53 IHC interpretation across pathologists.
Three ovarian cancer cell lines were selected to represent each TP53 mutation status — overexpression, wild-type, and null — and assembled into a single IHC p53 expression pattern control panel. The panel sections demonstrated consistent, clean, and clearly interpretable p53 staining across all three expression patterns, providing pathologists with an internal reference standard for each case.
Individual pathologist agreement was near-perfect when interpreting p53 IHC expression patterns using the cell line control panel as a reference.
Interrater reliability improved when pathologists used the cell line panel compared to standard tissue controls alone — a meaningful gain in a high-stakes interpretive setting.
The panel reduced the rate of null expression being misclassified as wild-type — the most clinically significant error in p53 IHC interpretation for gynecological pathology.
NGS was performed on the cell lines and on discordant cases where pathologist interpretations disagreed. Sequencing identified low-frequency variant mutations in some discordant cases — providing a molecular basis for the interpretive disagreement and supporting the use of NGS as a tiebreaker for cases with ambiguous or borderline p53 IHC staining.
“This study suggests the addition of a p53 cell line expression pattern control panel could potentially increase p53 interpretation accuracy for ovarian cancer subtypes.”
The panel has the potential to increase individual interrater reliability, support IHC antibody optimization, and direct difficult-to-interpret cases to next-generation sequencing for molecular confirmation.
The cell line control panel described in this study is the scientific foundation of PCI-AI’s TriControl™ product — providing null, wild-type, and diffuse expression profiles in a single FFPE cell block for use as a reference standard in clinical and research IHC workflows.
Null, wild-type, and diffuse expression profiles in a single FFPE cell block. Used as a reference standard for p53 IHC antibody optimization and clinical interpretation validation in gynecological pathology.
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